Writing Functions

Cell phones cost $89/month, plus the cost of the phone ($500). How much does the cell phone cost after using it for 8 months?

$1212

Cell phones cost $89/month, plus the cost of the phone ($500). Write a function for cost of the cell phone, C, after m, months.

C(m) = 500 + 89m

A graph that has a "V" shape

The function contains absolute value, like y = |3x|

A graph that has a parabola, or "U" shape

The function contains an exponent, like f(x) = 4x-squared

A graph that is a straight line

The function is linear.

Write a function for the total distance d(n) traveled after n hours at a constant speed of 45 miles per hour.

d(n) = 45n

Salad at the Whole Foods salad bar is $8.99/pound. Write a function, f(x), to describe the function.

f(x) = 8.99x

x f(x) 1 5 2 6 3 7 4 8

f(x) = x + 4

x f(x) 1 -1 2 0 3 1 4 2

f(x) = x - 2

x y 1 2 2 4 3 6 4 8

y = 2x

x y 1 1 3 9 6 36 9 81

y = x-squared (x to the second power)